Vaccuum-pan.



No. 722,519. PATENTBD MAR. -10, 1903. J. LANG, M. BLAKE & R. H. SMART. VACUUM PAN.

APPLIGATION FILED JULY 17. 1902.

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No. 722,519. PATENTED MAR. 10, 1903. J.' LANG, BLAKE 6: R. H. SMART. VACUUM PAN.

APPLICATION FILED JULY 17, 1902.

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UNITED ST TES PATENT OFFICE,

JOHN LANG, MATTHEW BLAKE, AND ROBERT H. SMART, OF GREENOCK, SCOTLAND; SAID LANG ASSIGNOR TO SAID BLAKE AND SMART.

VAC U U M -PAN.

SPECIFICATION forming part of Letters Patent No. 722,519, dated March 10, 1903. Application filed July 17, 1902. Serial No. 115,987. (No model.)

To all whom, it 11060; concern.-

Be it known that we, JOHN LANG, MATTHEW BLAKE, and ROBERT Ho WIE SMART, subjects of the King of Great Britain and Ireland, and residents of Greenock, Renfrewshire, Scotland, have invented certain new and useful Improved Sugar-Vacuum-Pan Apparatus, of

which the following is a specification.

This invention relates to an improved ap paratus whereby sugar liquors or syrups may be fed into vacuum-pans in a more satisfactory and rapid manner than has been attained hitherto, with a corresponding improvement in the sugar crystals produced therefrom.

In sugar solutions it has been ascertained that the most satisfactorycrystallization takes place when the mother liquor or syrup is maintained at a degree of supersaturation or concentration corresponding to its purity. Du r-' ing the progressive filling of a vacuum-pan after crystals or grain have first been formed the mother-liquor gradually decreases in purity and increases in viscosity. The viscosity tends to retard quick crystallization, and the high supersaturation otherwise desirable in the mother liquor or syrup must be gradually decreased in order to maintain a uniform crystallization.

The usual practice in feeding liquors or syrups to the vacuum-pan after crystals have first been formed is to admit certain quantities intermittently, according to the degree of supersaturation of the mother liquor or syrup as ascertained by the attendant by means of the proof-stick. This intermittent feeding is unsatisfactory, because the supersaturation or concentration of the mother-liquor or syrup is usually too high at the beginning of the feed or drink and too low at the finish to maintain the most rapid and uniform crystallization. Syrup and liquor fed in the usual manner has been unsatisfactory from yet another cause-namely, the temperature of the liquor or syrup introduced into the pan in the majority of cases is considerably lower than the boiling mass within it, and the inevitable result of feeding this relatively cold liquor or syrup into the hot mass is to promote a minute independent crystallization or false grain. Some attempts have been made to feed liquors and syrups into the pan continuously by providing the storage-tanks with steam-coils or other means of raising the temperature; but owing to the impossibility of properly controlling same these attempts have hitherto failed, especially by reason of overheating and consequent decolorization.

By means of our improved apparatus we are enabled to feed liquors and syrups continuously, and during the operation we are able to keep the temperature under proper control. In the case of liquors and juices as commonly used in refineries or factories, which are under saturated solutions at ordinary atmospheric temperatures, we heat them up to a temperature corresponding to that of the boiling mass within the pan; but in the case of supersaturated syrups it will be necessary to raise the temperature of the ingoin g syrup several degrees higher than the temperature within the pan for the purpose of melting out within our feeding apparatus the minute crystallization contained in this supersaturated solution in its relatively colder state. In our improved apparatus we successfully control the amount of heat which is imparted to the ingoing liquor in a manner which has not been attained hitherto, and the apparatus for the accomplishment of this we will'now proceedto describe by the aid of the accompanying drawings, in which- Figure 1 is an elevation showing our improved apparatus interposed between liquorstorage tank and vacuum-pan, and Fig. 2 is an elevation showing a modification of same.

In both figures like letters of reference designate the same parts throughout.

Referring to Fig. 1, A is the improved liquor or syrup feeding apparatus. B is the liquor or syrup storage tank. 0 is the vacuumpan. The liquor or syrup feeding apparatus A is provided with a steam-drum q, having, as here shown, tubes b similar to those provided in the steam-drums of ordinary multiple effect steam-evaporating apparatus; but the drum may be subdivided into compartments and the liquor be made to flow up and down through one or more tubes to give a longer heating-circuit. c is the steam-entry pipe into the drum or calandria. d is the steam-regulating valve, and e the condensedwater pipe from the steam-drum; f, the liquor or syrup pipe connecting storage-tank B with the lower end of the liquor or syrup feeding apparatus A. g is the regulating-valve for feeding the liquor or syrup; h, the liquor or syrup overflow and inverted siphon pipe from the feeding apparatus A into the pan 0; j, the Vacuum connecting-pipe between the feeding apparatus A and the vacuumpan 0, and k is the valve for regulating the degree of vacuum in the feeding apparatus A. Instead of the vacuum connecting-pipe j with the valve being connected to the airspace in the vacuum-pan same may be connected directly with the vacuum-pump which maintains the vacuum in the pan.

This improved apparatus is used for continuously feeding a pan in which the crystal or grain has been'already formed, as follows: By opening the valve 01 steam is admitted into the drum or calandria a. The valve 9, admitting the liquor or syrup from storagetank B, is then opened, and the liquor or syrup is drawn into feeding apparatus A in consequence of the vacuum in this apparatus due toits communication with the pan through the overflow and inverted siphon-pipe h. We assume meantime that the direct vacuum connection to feeding apparatus A through pipej and valve 7c is closed. The degree of vacuum, and consequently temperature, within the feeding apparatus A willdepend upon the height of leg of the inverted siphon-pipe it within the vacuum-pan O. In the case of feeding syrups alone it will be satisfactory to construct the siphon-leg of pipe h of sucha length and diameter as to heat the syrups to the necessary intensity within the feeding apparatus A without opening to any extent the direct connection through valve 7t; and pipej to the vacuum-pan. In feeding liquors, however, when a less degree of temperature is desired valve is may be considerably opened vin-order to more nearly equalize the vacuum and temperature in feeding apparatus A to that maintained within the vacuum-pan C.

The liquor or syrup in being fed from the storage-tank into the vacuum pan rises through tubes b of the feeding apparatus A, and thus becomes heated, and that only to the degree desired by the attendant, by the manipulation of the vacuum-valve It. The liquor or syrup in flowing up through the tubes of the feeding apparatus A overflows along the inverted siphon-pipe h and from thence into vacuum-pan O. The extent to which valved and feed-valve g are opened will depend materially upon the supersaturation of the mother-liquor within the pan; but the attendant may easily ascertain from time to time by means of the proof-stick if the continuous feed to which valve may be set is maintaining the contents of the pan at the desired degree of supersaturation to produce the most rapid and uniform crystallization. As the contents of the pan increase with the continuous feed, obviously the feed-valve g and steam-valve 01 will require to be more and more opened in proportion as the growing mass within the pan becomes greater, the increased viscosity of the mass also demanding a less degree of supersaturation, and consequently an increased volume of liquor or syrup.

The feeding apparatus will naturally be provided with a Bourdon vacuum-gage and thermometer, so that the attendant may accurately gage at any time the conditions under which the liquors or syrups are being fed into the pan and may adjust the same by the valves of the apparatus previously described.

Instead of the feed-pipeh terminating in an inverted siphon, as illustrated, the pipe may descend vertically to near the bottom of the pan, and thereby feed the liquor or syrup from the bottom end of same, the siphon effect being obtained from the dip into the contents of the pan, the seal naturally becoming greater as the contents of the pan increase.

In Fig. 2 we show a modification of our feeding apparatus in which we dispense with the regulating vacuum connection j and valve 70 between the feeding apparatus A and vacuum-pan O. A is the feeding apparatus previously described. h is the overflow feedpipe to vacuum-pan, which in this case does not terminate in an inverted siphon, but is open and free to the vacuum or air-space in the vacuum-pan O. This overflow feed-pipe 72, is of such adiameter as to conduct liquors to the vacuum-pan C and at the same time maintain a constant vacuum within the feeding apparatus A similar to that within'the pan 0.

In a refinery, a feeding apparatus with the connection as shown in Fig. 2 will only be satisfactory for feeding clear or under-saturated liquors to a vacuum-pan; but it will be evident thatwhere highly-concentrated syrups are to be fed to the pan a direct temperature controlling valve and connection, in conjunction with an inverted siphon feed or dip pipe, will be necessary to obtain the best result, as previously described.

In our illustration of the feeding apparatus, as in Fig. 2, We show an ascending liquor-pipe within the steam-drum in the form of a continuous coil 19', the liquor being inside the coil-pipe and the steam inside the drum a in contact with the outside of the ascending pipe; but it is evident the heat may be applied to the liquor by any system of steampiping-namely, straight, bent or coiled, vertical or horizontal, as adopted in many feedwater heaters. The area and capacity of the liquor-pipes from the storage-tanks to the feeding apparatus and from the feeding apparatus to the pan may be such that the latter may be entirely charged throughoutin the first instance, previous to forming crystals or grain in the pan, or the apparatus may be reserved entirely for the continuous feed after crystals or grain have been formed, the first charge having been drawn in by the usual charging-cock.

Having now described our invention, what we claim, and desire to secure by Letters Patent, is-

1. In vacuum-pan apparatus for producing sugar in crystals, the combination of the vacunrn-pan with a syrup-storage tank and an interposed heating vessel connected to the storage-tank and having at its upper part both a connection to the vacuum and an overflowpipe for the syrup to the pan, all substantially as described.

2. In vacuum-pan apparatus for producing sugar in crystals, the combination of the vacuum-pan with a syrup-storage,tank and an interposed heating vessel connected to the storage-tank and having at its upper part both a connection to the vacuum and an overflow siphon-pipe for the syrup to the pan, all substantially as described.

3. In vacuum-pan apparatus for producing sugar in crystals, the combination of the vacuum-pan with a syrup-storage tank and an interposed heating vessel having its lower end connected to the storage-tank and having at its upper end both a connection to the vacuum and an overflow-pipe for the syrup to the pan, substantially as described.

4. In vacuum-pan apparatus for producing sugar in crystals, the combination of the vacuuin-pan with a syrup-storage tank and an interposed heating vessel having its lower end connected to the tank and having at its upper end both a connection to the vacuum and an overflow siphon-pipe for the syrup to the vacuum-pan, substantially as described.

5. In vacuum-pan apparatus for producing sugar in crystals, the combination of the vacuum-pan with a syrup-storage tank and an interposed heating vessel connected to the tank and having at its upper end two pipes, one connected to the vacuum-producing means, and the other being an overflow-pipe for the syrup to the pan, all substantially as described.

6. In vacuum-pan apparatus for producing sugarin crystals, the combination of the vacuum-pan with a syrup-storage tank and an interposed heating vessel connected to the tank and having at its upper end two pipes, one connected to the vacuum-space in the pan and the other having an overflow-pipe for the syrup to the pan, all substantially as described.

7. In Vacuum-pan apparatus for producing sugar in crystals, the combination of the vacuum-pan with a syrup-storage tank and an interposed heating vessel connected to the tank and having at its upper end two pipes, one connected to the vacuum-producing means and the other having an overflow siphon-pipe for the syrup to the pan, all substantially as described.

8. A vacuum-pan and a storage-tank in combination with a closed vessel, heating means for the latter, a pipe from the tank to the vessel, a pipe from the vessel to the upper part of the pan, and a pipe from the vessel, terminating within the pan in a siphon, substantially as described.

9. A vacuum-pan and a storage-tank in combination with a closed heating vessel, a pipe from the tank to the vessel, a pipe from the upper part of the vessel to the upper part of the pan,aregnlating-valve in said upper pipe, and a pipe from said vessel to the pan terminatingin a siphon, substantially as described.

10. A vacuum-pan and a storage-tank in.

combination with a closed chamber, steamheating means and a regulating steam-valve for said vessel, a pipe having a regulatingvalve from the upper part of the vessel to the upper part of the pan, and a pipe at a lower level in the vessel terminating within the pan in a siphon, all substantially as described.

In testimony whereof we have signed our names to this specification in the presence of two subscribing witnesses.

JOHN LANG. MATTHEW BLAKE. R. H. SMART.

Witnesses:

ROB. S. MURRAY, WM. FYFE. 

